rocker arm wipe pattern

[Frankensteinz2]

Hey,

I have a question regarding the centering of the wipe pattern on the rocker arm. I went all stock with my rebuild so when it came to lash pads, I called MSA and asked for whatever came stock on the car and figured if i had any wipe pattern issues to work from there. I performed the wipe pattern test and i am off center towards the valve side. I called MSA to find out what the stock thickness they sent me and he said .127. Which also happens to be the thinest they have. So normal logic of going with a thinner lash pad to move the pattern towards the pivot won't work. Then he suggested shimming up the towers. I already have one shim under the towers. I was going to buy 2 more sets of shims and put them under to see the effects of the wipe pattern. Does this seem like the next logical step, or am i missing something? Also what affects are there on valve moment with the more shims. I already had .012 shaved from the head recently but before that I don't know, however it did have shims on it when i removed the head, so Im guessing it was shaved previously as well. Feelin a little over my head here.

Thanks

Frankie

[Mn_Z_Man]

When I had my head rebuilt, I made sure he measured the installed valve height, and then ground (tipped off) the valves to get them to the original height after the valve job. I was not able to find thinner pads either, only thicker for high perf cam builds. Good luck finding a shop that actually understands the L series head head geometry. I had 2 shops try to tell me the installed valve height didn't matter, thats what the lash adjustment is for, which is wrong. Depending on the amount they are off, its a toss up between shims and grinding the valve tips- maybe some of the more experienced members can chime in. The problem with grinding is I could not find an actual value for the stock installed height, and if you had shims in there it sounds like this is not the first rebuild. FYI, the L-series engine forum at hybridZ.org has a few good threads along this line.

Eric

[Frankensteinz2]

I don't have access to a good datsun shop here in indiana, so I was stuck with guys who only work on GM products . I went the expensive route and got new rocker arms this morning. My old rockers fit but they are grooved so I was forced to spend the 400 from MSA . I heard raising the towers will change compression, which i didn't want. But now thinking about it i might order the shims too and evaluate my opitions. Either way thought because my valves seem to be a little different heights I will end up using multiple size lash pads. I am curious how this will affect things, as you said its not the way to do it. Well thanks for the Help Eric. Hopefully this all turns out reasonably well .